This grant proposes a prospective longitudinal study of the seizure, psychiatric, neuropsychological, and vocational outcome of anterior temporal lobectomy (ATL) done for treatment of complex partial seizures of temporal lobe origin. ATL will be done by one surgical team but the patients will be randomized into two surgical groups. One patient group will have ATL done by a standard "en bloc" resection. The other patient groups will have complex partial seizures with ictal onset from mesial temporal structures and will not have a causal structural lesion (i.e., tumor or AVM) documented by MRI scan. The outcome of study will: (1) help clarify the role of hippocampus in nonlesional temporal lobe epilepsy, and (2) help clarify the which of several methods of ATL produce the best seizure outcome with minimal psychological and psychiatric impairment to patients. This proposal apples directly to the conclusion of the recent NIH consensus conference of Epilepsy Surgery.